Application of Photogrammetry to Estimates of Mine Pillar Damage and Strength

The use of terrestrial photogrammetry for characterizing changes and damage in rock masses was investigated. Repeat photogrammetry surveys of hard rock pillars were conducted and compared to calculate material loss and damage. Damage measured from photogrammetry was then compared to stresses predicted by Displacement Discontinuity modelling and was found to agree well with current empirical damage-stress relationships. Observed damage profiles were also input into Boundary Element models to correlate predicted stress concentrations with locations of observed damage. Modelled stress concentration locations and magnitudes agreed well with observed damage locations and stress magnitudes from the literature, respectively. Geological structures were characterized from photogrammetry models and used to generate Discrete Fracture Networks, which in turn provided inputs for Distinct Element numerical models. The observed damage was then used to calibrate numerical models which, pending additional calibration, can be used to improve understanding of pillar strength.